net: pcs: xpcs: make xpcs_do_config() and xpcs_link_up() internal

As nothing outside pcs-xpcs.c calls neither xpcs_do_config() nor
xpcs_link_up(), remove their exports and prototypes.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1svfMv-005ZIv-2M@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>